Compositions for making ene-thiol elastomers

ABSTRACT

In one aspect, the invention provides ene-thiol elastomers comprising the reaction product of a polythiol free of hydrophilic groups and having at least two thiol groups and an aromatic, heterocyclic, aliphatic, or cycloaliphatic polyene having at least two reactive unsaturated carbon to carbon bonds. In another aspect, the invention provides ene-thiol elastomer comprising the reaction product of (a) a thiol terminated oligomer comprising the reaction product of a polythiol having two thiol groups and a first polyene or mixture of polyenes having two reactive unsaturated carbon to carbon bonds; and (b) a second polyene or a mixture of polyenes having at least 5 percent functional equivalents of unsaturated carbon to carbon bonds from polyenes having at least three unsaturated carbon to carbon bonds. The ene-thiol elastomers of the invention have a weight increase of not more than 4 weight percent in 15 days at a temperature of 22° C. when immersed in a solution of 96 parts by weight water and 4 parts by weight n-butanol and/or a water vapor transmission rate of less than 50 g-mm/m 2 -day at 40° C. according to ASTM D814.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. patent application Ser.No. 09/567,944, filed May 10, 2000, now allowed, which claims thebenefit of U.S. Provisional Application No. 60/134,012, filed May 10,1999.

FIELD OF THE INVENTION

[0002] The invention relates to curable compositions used for makingene-thiol elastomers and cured ene-thiol elastomers made therefrom.

BACKGROUND OF THE INVENTION

[0003] Electronic circuits must be protected from exposure to harshcorrosive environments to maintain the performance of the electronicdevice. Many electronic circuits are used in environments where they areexposed to corrosive liquids. For example, adhesives and encapsulantsused to assemble ink jet cartridges must protect the flexible circuitthat controls the ink jet head from exposure to corrosive inks. Theseadhesives and encapsulants experience long term exposure to verycorrosive inks. If the adhesive or encapsulant degrade or excessivelyswell, the ink contacts and corrodes the circuit.

[0004] Thermosetting resins, frequently epoxy resins, are used toprotect circuits from corrosive environments. Epoxy resins have severalcharacteristics that limit their ability to perform well. Traces ofchloride ion, which are frequently present in epoxy resins, promote thecorrosion of circuits. Epoxy networks are somewhat hydrophilic and swellin aqueous environments because of the secondary alcohols produced inthe curing reaction. Epoxy networks are frequently difficult to fullycure in the time/temperature constraints of electronic manufacturingprocesses. Unreacted epoxy groups are prone to hydrolysis, formingglycols, which further decreases the water resistance of the network.These epoxy characteristics limit their use as adhesives andencapsulants in corrosive environments.

[0005] Many combinations of polyfunctional olefins and mercaptans havebeen used to prepare ene-thiol networks. While many monomers have veryattractive process characteristics (low viscosity and rapid UV curing),they do not provide networks having the requisite environmentalresistance to withstand highly corrosive aqueous environments. Polyetherdimercaptans are frequently used in ene-thiol compositions. Thesemonomers introduce hydrophilic units to the cured network, resulting inexcessive swelling in aqueous environments. Multifunctionalmercaptoacetates and propionates are other commonly used thiol monomers.In addition to their hydrophilic character, the ester linkage introducesa site for hydrolysis and network degradation.

SUMMARY OF THE INVENTION

[0006] In one aspect, the invention provides a curable composition formaking an ene-thiol elastomer comprising a mixture of a polythiol, or amixture of polythiols, having at least two thiol groups and free ofhydrophilic groups, and an aromatic, heterocyclic, aliphatic, orcycloaliphatic polyene having at least two reactive unsaturated carbonto carbon bonds, wherein the composition in cured form, when immersed ina solution of 96 parts by weight water and 4 parts by weight n-butanol,shows a weight increase of not more than 4 weight percent, preferably,not more than 3 weight percent, and more preferably, not more than 2.5weight percent in 15 days at a temperature of 22° C.

[0007] In another aspect, the invention provides a ene-thiol elastomercomprising the reaction product of a composition comprising a mixture ofa polythiol having at least two thiol groups and free of hydrophilicgroups and an aromatic, heterocyclic, aliphatic, or cycloaliphaticpolyene having at least two reactive unsaturated carbon to carbon bonds,wherein the ene-thiol elastomer, when immersed in a solution of 96 partsby weight water and 4 parts by weight butyl alcohol, shows a weightincrease of not more than 4 weight percent, preferably, not more than 3weight percent, and more preferably, not more than 2.5 weight percent in15 days at a temperature of 22° C.

[0008] In another aspect, the invention provides a curable compositionfor making an ene-thiol elastomer comprising a mixture of (a) a thiolterminated oligomer comprising the reaction product of a polythiolhaving two thiol groups and a first polyene or mixture of polyeneshaving two reactive unsaturated carbon to carbon bonds, and (b) a secondpolyene or a mixture of polyenes having at least 5 percent functionalequivalents of unsaturated carbon to carbon bonds from polyenes havingat least three unsaturated carbon to carbon bonds, wherein thecomposition in cured form, when immersed in a solution of 96 parts byweight water and 4 parts by weight n-butanol, shows a weight increase ofnot more than 4 weight percent, preferably, not more than 3 weightpercent, and more preferably, not more than 2.5 weight percent in 15days at a temperature of 22° C.

[0009] Generally, not more than 50 weight percent, preferably, not morethan 30 weight percent, more preferably, not more than 20 weightpercent, and even more preferably, none of the polythiol used to makethe oligomer has hydrophilic groups. The first and second polyenes ormixtures of polyenes may be the same or different. Preferred firstpolyenes include divinyl ethers, and cyclic polyenes. Preferredpolythiols include dimercaptodiethyl sulfide, 1,6-hexanedithiol, and1,8-dimercapto-3,6-dithiaoctane.

[0010] In another aspect, the invention provides a ene-thiol elastomercomprising the reaction product of a composition comprising the reactionproduct of (a) a thiol terminated oligomer comprising the reactionproduct of a polythiol having two thiol groups and a first polyene ormixture of polyenes having two reactive unsaturated carbon to carbonbonds and (b) a second polyene or a mixture of polyenes having at least5 percent functional equivalents of unsaturated carbon to carbon bondsfrom polyenes having at least three unsaturated carbon to carbon bonds,wherein the composition in cured form, when immersed in a solution of 96parts by weight water and 4 parts by weight n-butanol, shows a weightincrease of not more than 4 weight percent, preferably, not more than 3weight percent, and more preferably, not more than 2.5 weight percent in15 days at a temperature of 22° C.

[0011] Generally, not more than 50 weight percent, preferably, not morethan 30 weight percent, more preferably, not more than 20 weightpercent, and even more preferably, none of the polythiol used to makethe oligomer has hydrophilic groups. The first and second polyenes ormixtures of polyenes may be the same or different. Preferred firstpolyenes include divinyl ethers, and cyclic polyenes. Preferredpolythiols include dimercaptodiethyl sulfide, 1,6-hexanedithiol, and1,8-dimercapto-3,6-dithiaoctane.

[0012] In another aspect, the invention provides ene-thiol elastomerscomprising the reaction product of a composition comprising a mixture ofa polythiol having at least two thiol groups and free of hydrophilicgroups and an aromatic, heterocyclic, aliphatic, or cycloaliphaticpolyene having at least two reactive unsaturated carbon to carbon bonds,wherein the ene-thiol elastomers have a water vapor transmission rate ofless than 50, preferably less than 30, more preferably, less than 20g-m/mm²-day at 40° C. according to ASTM D814.

[0013] In another aspect, the invention provides ene-thiol elastomerscomprising the reaction product of a composition comprising the reactionproduct of (a) a thiol terminated oligomer comprising the reactionproduct of a polythiol having two thiol groups and a first polyene ormixture of polyenes having two reactive unsaturated carbon to carbonbonds and (b) a second polyene or a mixture of polyenes having at least5 percent functional equivalents of unsaturated carbon to carbon bondsfrom polyenes having at least three unsaturated carbon to carbon bonds,wherein the ene-thiol elastomers have a water vapor transmission rate ofless than 50, preferably less than 30, more preferably, less than 20g-mm/m²-day at 40° C. according to ASTM D814.

[0014] In another aspect, the invention provides an ene-thiol elastomercomprising the reaction product of (a) an unsaturated carbon to carbonbond terminated oligomer comprising the reaction product of a firstpolythiol having two thiol groups and a polyene or mixture of polyeneshaving two reactive unsaturated carbon to carbon bonds; and (b) a secondpolythiol or mixture of polythiols having at least 5 percent functionalthiol equivalents from polythiols having at least three thiol groups,wherein the ene-thiol elastomer shows a weight increase of not more than4 weight percent in 15 days at a temperature of 22° C. when immersed ina solution of 96 parts by weight water and 4 parts by weight n-butanol.

[0015] In other aspects, the invention provides a method of making theabove ene-thiol elastomers, and an article of manufacture comprisingelectrical or electronic components encapsulated in a ene-thiolelastomer of the invention.

[0016] The compositions of the invention preferably contain a freeradical initiator and more preferably, a photoinitiator.

[0017] As used herein, the term “polythiols” refers to simple or complexorganic compounds which are substantially free of disulfide linkages andhave a multiplicity of pendant or terminally positioned —SH functionalgroups per molecule.

[0018] As used herein, the term “free of hydrophilic groups” when usedto describe polythiols means polythiols devoid of any ether, ester,hydroxyl, carbonyl, carboxylic acid, sulfonic acid linkages or groupswithin or pendant from the polythiol molecule.

[0019] As used herein, the term “polyene” refers to simple or complexspecies of alkenes having at least two reactive unsaturated carbon tocarbon bonds per molecule.

[0020] As used herein, the terms “di functional”, “trifunctional”, and“tetrafunctional” when used to describe polythiols and polyenes meanspolythiols having two, three, and four thiol groups and polyenes havingtwo, three, and four reactive unsaturated carbon to carbon bonds.

[0021] The compositions of the invention are generally low viscosityliquids that can be uniformly coated onto flexible circuitry and rapidlycured by actinic radiation. The resulting ene-thiol elastomers aretough, flexible, and resist swelling or chemical degradation by waterand corrosive components of inks.

[0022] One of the unique properties of the ene-thiol elastomers of theinvention is the combination of flexibility with resistance to swellingand degradation by water and corrosive environments. Brittle thermosetresins, such as conventional epoxies, may provide reasonable resistanceto swelling by corrosive components of inks but are prone to crackingwhen used on a flexible circuit. The resulting cracks then provide apath for the corrosive liquid to penetrate the coating and corrode thesubstrate. Low Tg epoxies, acrylates, urethanes or other elastomericthermosetting resins, which are flexible and resist cracking, aregenerally prone to degradation by these corrosive liquids. The ene-thiolelastomers of the invention provide the swelling resistance of brittleglassy epoxy resins with elastomeric flexibility.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The polythiols of the invention have at least two thiol groupsand are free of hydrophilic groups. Useful polythiols are alsosubstantially free of disulfide linkages that would impart chemicaland/or thermal instability to the crosslinked or cured network. Thepolythiols may be aliphatic or aromatic and may be monomeric orpolymeric. Useful polythiols have the formula:

[0024] where m=2-12, n=2-12, q=0-4, where m and n can be the same ordifferent; or the formula H—S—R—S—H, where R=C₅-C₈ cycloaliphaticradical.

[0025] The use of di-, tri-, and tetra-functional polythiols is alsocontemplated in the present invention.

[0026] Specific examples of useful polythiols include dimercaptodiethylsulfide; 1,6-hexanedithiol; 1,8-dimercapto-3,6-dithiaoctane;propane-1,2,3-trithiol;1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane;tetrakis(7-mercapto-2,5-dithiaheptyl)methane; and trithiocyanuric acid.The polythiols may be used alone or in combination with one another.

[0027] When using polythiols having two thiol groups, useful polyenes ofthe invention may be characterized by mixtures of those materials havingat least 5 percent functional equivalents of unsaturated carbon tocarbon bonds contributed by polyenes having at least three unsaturatedcarbon to carbon bonds. Preferred polyenes are heterocyclic, aliphatic,or cycloaliphatic diene, allyl ether, allyl ester, vinyl ether, styryl,(meth)acryl, allyl or vinyl compounds having at least two or threereactive unsaturated carbon to carbon bonds per molecule. Mixtures ofpolyenes, each having two and three unsaturated carbon to carbon bondsrespectively, are preferred. Specific examples includetriallyl-1,3,5-triazine-2,4,6-trione; 2,4,6-triallyloxy-1,3,5-triazine;1,4-cyclohexanedimethanol divinyl ether; 4-vinyl-1-cyclohexene;1,5-cyclooctadiene; and diallyl phthalate. Combinations of usefulpolyenes may also be used in the compositions of the invention. Thepolythiols and polyenes are present in the compositions and elastomersof the invention in a stoichiometric amount.

[0028] The composition of the invention may contain a free radicalinitiator, preferably a UV active free radical initiator, to cure orcrosslink the composition. Useful free radical initiators which are wellknown in the art and include the class of free radical initiators arecommonly referred to as “photoinitiators.” A preferred commerciallyavailable free radical initiator, also a photoinitiator, is IRGACURE651, available from Ciba Specialty Chemicals, Tarrytown, N.J.Alternatively, the compositions of the invention may also containthermally activated free radical initiators.

[0029] The compositions of the invention are generally made by mixing astoichiometric amount of one or more polythiols and one or more polyenesin an appropriate vessel. In the case of reacting polythiols andpolyenes, each having two thiol and unsaturated carbon to carbon bondsrespectively, it may be preferable to first form an oligomer using asub-stoichiometric amount of polyene and then reacting the oligomer witha polyene having at least three unsaturated carbon to carbon bonds toform the crosslinked elastomer. If a photoiniator is used, thecomponents may be mixed in the absence of actinic radiation and thenstored in the dark for extended periods of time. If desired, thecompositions of the invention may contain conventional inhibitors toprevent spontaneous radical polymerization.

[0030] One of the advantages of first preparing an oligomer by reactinga sub-stoichiometric amount of polyene having two unsaturated carbon tocarbon bonds with polythiol having two thiol groups is that theoligomer, having an increased molecular weight, may be vacuumdevolatilized so to substantially reduce the objectionable odorcharacteristics of polythiols. The resulting oligomers have very lowvapor pressures by virtue of their molecular weight and have littleodor, but may contain volatile sulfur containing compounds that causeobjectionable odor. The removal of such compounds results incompositions having low odor. Another advantage of first preparingoligomers is that such preparation allows the use of combinations ofpolyenes having different reactivities. For example, a polyene havingtwo unsaturated carbon to carbon bonds having low reactivity can be usedto prepare the oligomer and a mixture of polyenes having two and threeunsaturated carbon to carbon bonds having relatively high reactivity canbe used to react with the oligomer to form the elastomer.

[0031] Alternatively, the ene-thiol elastomers of the invention may bemade using a polythiol having either three or four thiol groups permolecule and a polyene oligomer terminated with unsaturated carbon tocarbon bonds. Such polyene oligomers can be made from the reaction of apolyene having two unsaturated carbon to carbon bonds and asub-stoichiometric amount of a polythiol having two thiol groups permolecule. Elastomers can be made by reacting the polyene oligomer withpolythiols, wherein at least 5 percent of the functional equivalents ofthiol is provided by polythiols having at least three thiol groups permolecule.

[0032] The compositions can then be applied to the desired substrate,for example, electrical connectors, or other electrical components andthe like, and exposed to electron beam radiation. If the compositioncontains a photoinitiator, the composition may be exposed to any form ofactinic radiation, such as visible light or UV radiation, but ispreferably exposed to UVA (320 to 390 nm) or UVV (395 to 445 nm)radiation. Generally, the amount of actinic radiation should besufficient to form a solid mass that is not sticky to the touch.Generally, the amount of energy required curing the compositions of theinvention ranges from about 0.4 to 20.0 J/cm².

Glossary

[0033] DMDS—Dimercaptodiethyl sulfide (Structure 1), HSC₂H₄SC₂H₄SH, CASNo. 3570-55-6, available from Itochu Specialty Chemical Inc.

[0034] DMDO—1,8-dimercapto-3,6-dioxooctane, HSC₂H₄OC₂H₄OC₂H₄SH, CAS NO.14970-87-7, available from Itochu Specialty Chemical Inc.

[0035] EBMP—Ethylene bis(3-mercaptopropionate), HSC₂H₄COOC₂H₄OOCC₂H₄SH,7575-23-7, available from Evans Chemetics Division of HampshireChemicals.

[0036] CAPCURE® 3-800—Trifunctional mercaptan terminated liquid polymer,available from Henkel Corporation.

[0037] HDT—1,6-hexanedithiol, HSC₆H₁₂SH, CAS No. 1191-43-1, availablefrom Aldrich Chemical Company.

[0038] IGRACURE 651—2,2-Dimethoxy-2-phenylacetophenone,C₆H₅COC(OCH₃)₂C₆H₅, CAS No. 24650-42-8, available from Ciba SpecialtyChemicals.

[0039] TAIC—Triallyl-s-triazine-2,4,6(1H,3H,5H)-trione, (Structure 2),CAS No. 1025-15-6, available from Aldrich Chemical Company.

[0040] TAC—Triallyloxy-1,3,5-triazine, (Structure 3), CAS No. 101-37-1,available from Aldrich Chemical Company.

[0041] Rapi-Cure CHVE—1,4-cyclohexanedimethanol divinyl ether (Structure4), CAS No. 17351-75-6, available from International Specialty Products.

[0042] VCH—4-vinyl-1-cyclohexene (Structure 5), CAS No. 100-40-3,available from Aldrich Chemical Company.

[0043] COD—1,5-cyclooctadiene (Structure 6), CAS No. 111-78-4, availablefrom Aldrich Chemical Company.

[0044] DAP—diallyl phthalate (Structure 7), CAS No. 131-17-9, availablefrom Aldrich Chemical Company.

[0045] PEGDE—poly(ethylene glycol) divinyl ether (Structure 8), CAS No.50856-26-3, available from Aldrich Chemical Company.

[0046] AIBN—2,2′-azobisisobutronitrile, CAS No. 78-67-1 , available fromAldrich Chemical Company. It is used as a thermal free radicalinitiator.

[0047] NPAL—tris(N-nitroso-N-phenylhydroxylamine)aluminum salt, CAS No.15305-07-4, available from First Chemical Corporation. It is used as aradical inhibitor.

[0048] Oligomer Preparation

[0049] A variety of oligomers with different backbone structures weresynthesized. DMDS was chosen as a monomer to minimize the amount ofether linkages in the backbone and maximize the number of thioetherlinkages. The oligomers were prepared by the addition of a dimercaptanto a diolefin under free radical conditions. The molecular weight of theoligomer was controlled by reaction stoichiometry. The reactions werecarried out either thermally or photochemically. Polymerizations carriedout with less reactive olefins such as VCH and COD were more successfulusing the photochemical method.

[0050] Thermal Procedure

[0051] A dimercaptan or mixture of dimercaptans was weighed into aflask, AIBN was added, and the flask was heated to 65° C. A diolefin wasadded dropwise to the dimercaptan solution at a rate to maintain thetemperature in the flask between 90-100° C. After the addition, theoligomer was stirred for 4 hours, and the temperature was maintained at75-80° C. The reaction product was checked by ¹H NMR and ¹³C NMR todetermine whether any olefin groups remained. If olefin was stillpresent in the product mixture, additional AIBN was added and theoligomer was stirred at 75-80° C. for an additional 5 hours, when theamount of olefin remaining was determined to be less than 4 percent by¹H NMR. The oligomers in Table 1 were prepared using the thermalprocedure.

[0052] Alternative Thermal Procedure

[0053] The reaction was carried out as described above; however, 0.5percent AIBN was dissolved into the diolefin, and the resulting solutionwas added to the dimercaptan. TABLE 1 Initiator Reaction Target DMDSCHVE DAP Wt. % Time M_(N) Oligomer 1 100.3 g 112.7 — 0.3% 4 hr 2800Oligomer 2 30.37 g 25.45 — 0.5% 4 hr  830 Oligomer 3 24.57 g — 35.06 g0.6% 9 hr 2800 Oligomer 4 25.20 g — 25.24 g 0.75%  9 hr  830

[0054] Photochemical Procedure

[0055] A dimercaptan, a diolefin, and 0.5 weight percent IRGACURE 651were weighed into a glass jar. The contents of the jar were shaken andwere irradiated for 4 hours with two GTE 15 watt Sylvania 350 nm blacklight bulbs having a power output of 1 mW/cm². Additional IRGACURE 651was added, and the oligomer was heated to 80° C. The oligomer wasirradiated again for several hours. The reaction was considered completewhen greater than 95 percent of the olefin groups had reacted as judgedby ¹H and ¹³C NMR. The oligomers in Table 2 were made using thephotochemical procedure. TABLE 2 Total Exposure Target DMDS VCH CODInitiator Time M_(N) Oligomer 5 39.83 g 25.41 g — 1.3% 16 hr 2800Oligomer 6 30.02 g 15.17 g — 0.5%  4 hr  830 Oligomer 7 35.03 g — 22.33g 1.0% 12 hr 2800 Oligomer 8 40.25 g — 21.53 g 1.2% 12 hr 1000

[0056] Oligomers 9 and 10 are described in Table 3 and contain acombination of VCH, which contains no oxygen ether linkages, and CHVE,which has reactive vinyl ether groups. DMDS, VCH, and IRGACURE 651 wereweighed into a glass jar. The contents were shaken and irradiated for 4hours with two GTE 15 watt Sylvania 350 nm black light bulbs having apower output of 1 mW/cm². CHVE and IRGACURE 651 were added to theresulting oligomer, and the solution was irradiated again for 2 hours.TABLE 3 Total DMDS VCH CHVE Initiator Target M_(N) Oligomer 9 17.12 g5.38 g  9.76 g 0.5% 2800 Oligomer 10 25.09 g 6.05 g 10.98 g 0.6%  830

[0057] Oligomers 11 and 12 are described in Table 4 and were preparedwith a mixture of DMDS and DMDO. The alternative thermal procedurelisted above was used, and 0.5 percent AIBN was the catalyst level foreach reaction. For Oligomer 11, DMDS and DMDO were used in a 70:30ratio, and for Oligomer 12 DMDS and DMDO were used in a 50:50 ratio. Forboth oligomers, there are more sulfur atoms than oxygen atoms in thebackbone. TABLE 4 DMDS DMDO CHVE Target M_(N) Oligomer 11  9.00 g  7.62g 17.08 g 2800 Oligomer 12 15.00 g 17.72 g 24.61 g  830

[0058] Oligomers 13-18 are described in Table 5 and contain more oxygenatoms than sulfur atoms in the backbone and were prepared for purposesof comparison. The alternative thermal procedure listed above was used,and 0.5 percent AIBN was the catalyst level for each reaction. TABLE 5DMDS DMDO CHVE PEGDE Target M_(N) Oligomer 13 — 16.00 g 15.01 g — 2800Oligomer 14 — 15.12 g 10.29 g —  830 Oligomer 15 16.01 g — — 22.16 g2800 Oligomer 16 25.50 g — — 25.53 g  830 Oligomer 17  9.68 g 11.49 g —26.71 g 2800 Oligomer 18 12.51 g 14.78 g — 24.57 g  830

[0059] Preparation of DMDT

[0060] DMDT, 1,8-dimercapto-3,6-dithiaoctane (Structure 9), was preparedfrom 3,6-dithia-1,8-octadiol using the method of Cooper et al. with theexception that 38 percent HCl was used in place of 48 percent HBr in thesynthesis. Wolf, R. E., Jr.; Hartman, J. R.; Storey, J. M. E.; Foxman,B. M.; Cooper, S. R. J. Am. Chem. Soc. 1987, 109, 4328-4335.

EXAMPLES Examples 1-4

[0061] Examples 1-4 were prepared by mixing the components in the ratiosidentified in Table 6. The resins were cured by placing 6 grams of theliquid mixture into a 70 mm diameter aluminum dish, heating to 50° C.,and irradiating for 1 hour under two GTE 15 watt Sylvania 350 nm blacklight bulbs having a power output of 1 mW/cm². Clear 1.4 mm thickelastomeric specimens were obtained. TABLE 6 Example 1 Example 2 Example3 Example 4 TAIC  5.0 g —  5.0 g — TAC —  5.0 g —  5.0 g DMDS  4.6 g 4.6 g — — HDT — —  4.5 g  4.5 g IGRACURE 651 0.048 g 0.048 g 0.048 g0.048 g

Comparative Examples 1-5

[0062] Comparative Examples 1-5 were prepared by mixing the componentsin the ratios identified in Table 7. The resins were cured by placing 6grams of the liquid mixture into a 70 mm diameter aluminum dish, heatingto 50° C., and irradiating for 1 hour under two Sylvania 350 nm blacklight bulbs having a power output of 1 mW/cm². Clear 1.4 mm thickelastomeric specimens were obtained. TABLE 7 Comparative ComparativeComparative Comparative Comparative Example 1 Example 2 Example 3Example 4 Example 5 TAIC  5.0 g  5.0 g  5.0 g — — TAC — — —  5.0 g  5.0g DMDO  5.46 g — —  5.46 g — EBMP —  7.14 g — —  7.14 g CAPCURE ® — —16.2 g — — 3-800 IRGACURE 0.053 g 0.061 g — 0.053 g 0.061 g 651

[0063] Absorption Performance at 60° C.

[0064] The swelling volume of the cured Examples 1-4 and ComparativeExamples 1-5 were measured. Specimens weighing approximately 0.5 gramswere cut from the 1.4 mm thick films prepared above, dried for 1 hour ina vacuum oven at a temperature of 100° C. and pressure of 2 torr (266Pa) and carefully weighed before immersion in distilled water and in a96/4 mixture, by weight, of water/n-butyl alcohol at 60° C. The sampleswere removed from the liquids carefully patted dry with a paper towel,and weighed after 24 and 72 hours. The percent weight gain wascalculated by the following formula: (swollen weight)-(originalweight)/(original weight). The results of this experiment are reportedin Table 8. TABLE 8 % Weight Gain % Weight Gain in Water/n - butanol inWater/n - butanol % Weight Gain % Weight Gain 96/4 96/4 in Water (24 hr)in Water (72 hr) (24 hr) (72 hr) Example 1 1.0% 1.0% 1.2% 1.4% Example 20.8% 0.8% 2.42%  3.19%  Example 3 0.6% 0.6% 2.1% 2.7% Example 4 0.6%0.6% 3.42%  4.12%  Comparative 2.1% 2.1% 6.4% 6.3% Example 1 Comparative2.9% 3.6% 6.2% 7.3% Example 2 Comparative 8.5% 8.0% 22.4%  18.76% Example 3 Comparative 1.8% 1.8% 7.7% 7.8% Example 4 Comparative 2.0%2.4% 8.0% 7.8% Example 5

[0065] The data in Table 8 clearly show that the ene-thiol resins ofExamples 1-4 are much more resistant to swelling in water and inwater/n-butanol than Comparative Examples 1-5. The water/butanol mixturewas used to simulate the swelling characteristics of corrosive inks. Thepresence of a nonaqueous component such as butanol significantlyincreases the swelling of the elastomer network as compared to swellingobtained using water alone. Many available inks have significant amountsof water miscible solvents which typically increase swelling of and, ingeneral, facilitates degradation of the elastomer network.

[0066] The absorption data in Table 8 also clearly demonstrates theimportance of maximizing thioether content and minimizing hydrophilicunits in the network. The performance of Examples 1 and 2 when comparedto that of Comparative Examples 1 and 4 is particularly surprising. Thedimercaptans, DMDO and DMDS, are structurally very similar and thephysical properties of the cured networks before exposure to water werevery similar. However, the resistance to water and water/n-butanol swellof DMDO and DMDS networks is very different.

[0067] Absorption Performance at 22° C.

[0068] The swelling of Examples 1-4 and Comparative Examples 1-4, wasalso measured in a 96/4 mixture of water/n-butanol at room temperature(22° C.) and in Lexmark inks. The cyan ink is from Lexmark's colored inkjet cartridge, part number 12A1980. The composite ink is a mixture ofcyan, magenta, and yellow inks from Lexmark's colored ink jet cartridge,part number 12A1980. The black ink is from Lexmark's black ink jetcartridge part number 12A1970. Specimens weighing approximately 0.2 gramwere cut from the 1.4 mm thick films prepared above, dried for 24 hoursat 60° C. in a vacuum oven, and weighed before immersion in the ink orwater/n-butanol solution. The samples swelled in the water/n-butanolmixture or water were immersed at room temperature and removedperiodically, carefully dried with a paper towel, and weighed. Thesamples swelled in the inks were immersed in ink and stored at 60° C.They were periodically removed, and the samples were rinsed with waterto remove the ink. They were patted dry with a paper towel and carefullyweighed. This is the standard swelling procedure used in all examplesand comparative examples. The percentage weight gain was calculated fromthe formula: (swollen weight)−(original weight)/(original weight).Samples soaked in water/n-butanol or water were soaked for a total of 15days. After 15 days, the samples were dried in a vacuum oven at 60° C.for 48 to 96 hours to remove the water and n-butanol from the samples.This dried down weight was recorded and used to report a correctedweight gain for the 15 day swelling studies. The corrected percentageweight gain for the 15 day swelling studies was calculated from thefollowing formula: (swollen weight)−(dried down weight)/(dried downweight). This number is reported to correct for any weight losses in thesamples due to extraction by the water or water/n-butanol mixture of anyuncured material.

[0069] The data in Table 9 show the percentage weight increase inwater/n-butanol and ink for the examples and comparative examples. Thedata in Table 9 clearly indicate that Examples 1-4, containing no oxygenether or ester linkages in the dimercaptan backbone, are much moreresistant to swelling in water/n-butanol and ink than the comparativeexamples, which contain ether or ester linkages in the backbone.Dramatic weight losses over several days in ink were observed forComparative Examples 2 and 5, which contain easily hydrolyzed esterfunctional groups. TABLE 9 % Weight Gain in Water/n-butanol 96/4 (7day/15 day Composite (5 Cyan (5 day/20 Black (5 day/20 corrected^(a))day/20 day day day Example 1 0.46%/0.60% 1.26%/2.01% 1.23%/1.57%1.22%/1.34% Example 2 0.71%/0.99% 1.80%/2.07% 1.77%/1.96% 1.04%/1.30%Example 3 0.64%/0.74% 1.52%/2.31% 1.50%/2.10% 1.04%/1.04% Example 41.00%/1.35% 2.25%/2.38% 1.93%/1.93% 1.00%/1.00% Comparative 3.76%/4.20%4.65%/5.05% 5.06%/6.35% 3.56%/3.55% Example 1 Comparative 5.51%/6.61%7.33%/1.17%  9.86%/10.32%  7.98%/5.88%^(b) Example 2 Comparative4.46%/4.86% 4.94%/5.11% 5.39%/5.29% 3.38%/3.14% Example 4 Comparative3.63%/4.41% 6.97%/9.61% 6.87%/9.19% 4.93%/0.69% Example 5

Example 5

[0070] Samples 1-20 are examples of the invention. These samplesexemplify that ene-thiol oligomers containing small amounts of oxygenether linkages and large amounts of thioether linkages can becrosslinked to form solvent, water, and ink resistant elastomericnetworks. The samples were prepared by mixing oligomers with either TAICor TAC as described in the table below. The samples were mixed with 0.5percent IRGACURE 651 and poured into an aluminum dish or poured into amold made from two glass plates covered with release liner separated bya {fraction (1/16)} inch silicone spacer. The samples were irradiatedfor 1 hour with two GTE 15 watt Sylvania 350 nm black light bulbs havinga power output of 1 mW/cm². The preparation of the samples is describedin Table 10. TABLE 10 Oligomer Crosslinker Oligomer Weight CrosslinkerWeight Sample 1 Oligomer 1 19.22 g TAC 0.97 g Sample 2 Oligomer 1 17.52g TAIC 0.89 g Sample 3 Oligomer 2  5.21 g TAC 1.00 g Sample 4 Oligomer 212.18 g TAIC 2.33 g Sample 5 Oligomer 3 16.30 g TAC 0.99 g Sample 6Oligomer 3 15.04 g TAIC 0.94 g Sample 7 Oligomer 4  5.03 g TAC 1.08 gSample 8 Oligomer 4  5.03 g TAIC 1.09 g Sample 9 Oligomer 5 16.53 g TAC0.88 g Sample 10 Oligomer 5 13.92 g TAIC 0.74 g Sample 11 Oligomer 6 5.15 g TAC 1.03 g Sample 12 Oligomer 6 13.09 g TAIC 2.61 g Sample 13Oligomer 7 15.88 g TAC 0.98 g Sample 14 Oligomer 8 10.17 g TAC 1.51 gSample 15 Oligomer 9 15.97 g TAC 0.91 g Sample 16 Oligomer 10  5.11 gTAC 0.98 g Sample 17 Oligomer 10  5.51 g TAIC 1.05 g Sample 18 Oligomer11 16.13 g TAC 0.87 g Sample 19 Oligomer 12  4.11 g TAC 0.82 g Sample 20Oligomer 12  4.07 g TAIC 0.81 g

[0071] The ink and moisture resistance for Samples 1-20 is shown inTable 12. The {fraction (1/16)} inch samples were cut into piecesweighing approximately 0.2 gram, and the standard swelling proceduredescribed above was used. Samples 1-20 swelled less than 4 percent in96/4 water/n-butanol at room temperature in 15 days. Additionally, mostof these samples did not pick up more than 2 percent weight after beingimmersed in water at 60° C. for 15 days. Also remarkable is that each ofthese materials swelled less than 4 percent at 60° C. in each of theinks that were tested. These elastomers have low crosslink densities,either 1000 or 3000 molecular weight between crosslinks. This exampledemonstrates that lightly crosslinked materials in which the number ofthioether groups is maximized and the amount of oxygen ether groups isminimized are resistant to swelling by ink, water, and solvent.

Example 6

[0072] Sample 21 was prepared to exemplify that a dimercaptan monomercontaining four sulfurs in the backbone can be used to prepare inkresistant elastomeric networks. It was prepared by mixing DMDT (2.03grams), TAIC (1.57 grams), and IRGACURE 819 (0.018 gram) in an aluminumdish on a hot plate. It was passed through a Fusion processor 10 timesat 20 ft./min. using the Fusion V Bulb.

[0073] Sample 21 was tested in water and water/n-butanol using thestandard swelling procedure. The water/n-butanol and water resistance ofSample 21 is shown in Table 12 and is very similar the data obtained forExample 1 which contains DMDS in its backbone. The equilibriumwater/n-butanol uptake at room temperature is approximately 0.5 percent,and the equilibrium water uptake at 60° C. is approximately 1 percent.Therefore, DMDT, which contains no oxygen ether or ester linkages, is adimercaptan monomer that can be used to make resins that are resistantto swelling in ink, water, or solvent.

Example 7

[0074] Samples 22 and 23 are described in Table 11 and exemplify anothermethod for synthesizing ink resistant elastomers using ene-thiolchemistry. In these samples, a small amount of difunctional olefinmonomer, CHVE, was added to a difunctional mercaptan and TAIC. Thesethree monomers form a low viscosity solution. The molecular weightbetween crosslinks can be adjusted by the ratio of CHVE and TAIC. Forthese samples, a dimercaptan monomer, CHVE, TAIC, 500 ppm NPAL, and 0.5percent IRGACURE 651 were combined and stirred thoroughly. The NPAL wasadded to prevent premature gelling of the resin. The liquid was pouredinto a mold made from two glass plates covered with release liners and a{fraction (1/16)} inch silicone spacer. The samples were irradiated for1 hour with two GTE 15 watt Sylvania 350 nm black light bulbs having apower output of 1 mW/cm². TABLE 11 DMDS DMDT CHVE TAIC Sample 22 8.04 g— 3.45 g 5.74 g Sample 23 — 9.18 g 2.84 g 4.70 g

[0075] Samples 22 and 23 were tested in water/n-butanol and water usingthe standard swelling procedure. The swelling of Samples 22 and 23 inwater/n-butanol and water is reported in Table 12 and is also quite low.The equilibrium water/n-butanol uptake is less than 1.5 percent for bothsamples, and the equilibrium moisture uptake is approximately 1 percent.Thus, solvent and moisture resistant resins can be prepared by mixing adimercaptan with a mixture of difunctional and trifunctional olefins andphotochemically curing the resulting solution.

[0076] Absorption Performance

[0077] Table 12 contains the absorption performance data. The swellingprocedures described above were used. The percentage weight gain in inkwas calculated from the formula: (swollen weight)−(originalweight)/(original weight). The corrected percentage weight gain inwater/n-butanol or water was calculated from the following formula:(swollen weight)−(dried down weight)/(dried down weight). To obtain thedried down weight, Samples 1-20 were dried for 48 hours, and Samples21-23 were dried for 96 hours. TABLE 12 Water/n-butanol 96/4 Water (7 (7day/15 day day/15 day Composite (7 Cyan (7 Black (2 day/7 corrected)corrected) day/15 day) day/15 day) day) Sample 1 2.30%/2.08% 0.90%/1.31%2.52%/2.45% 2.45%/2.38% 0.89%/0.71% Sample 2 2.29%/2.07% 0.89%/1.10%2.26%/2.31% 2.41%/2.58% 0.73%/0.58% Sample 3 2.01%/2.35% 0.63%/1.09%2.43%/2.17% 2.22%/2.53%   0.39%/−.13%  Sample 4 1.65%/2.26% 0.42%/1.06%2.10%/2.10% 2.28%/2.55% 0.54%/0.54% Sample 5 1.15%/1.87% 0.85%/1.37%2.81%/2.87% 2.47%/2.41% 0.45%/0.57% Sample 6 1.51%/1.93% 0.80%/1.43%2.62%/2.70% 2.50%/2.43% 0.60%/0.40% Sample 7 1.28%/1.73% 0.82%/1.28%2.27%/2.40% 2.45%/2.67% 0.60%/0.12% Sample 8 0.99%/1.37% 0.79%/1.13%2.26%/2.42% 2.36%/2.52% 0.51%/0.00% Sample 9 0.88%/1.17% 1.20%/2.80%1.97%/1.97% 2.29%/2.40% 0.30% Sample 10 0.71%/1.18% 0.52%/0.59%1.54%/1.39% 1.62%/1.68% 0.42% Sample 11 0.58%/0.95% 0.30%/0.73%1.16%/1.10% 1.55%/1.69% 0.48%/0.20% Sample 12 0.34%/0.43% 0.14%/0.48%1.13%/0.92% 1.47%/1.55% 0.43%/0.43% Sample 13 0.57%/0.91% 0.17%/1.38%0.84%/1.25% 0.85%/0.92% −0.24%/−0.30% Sample 14 0.45%/0.68% 0.11%/1.05%1.09%/1.03% 0.94%/1.00% 0.32%/0.00% Sample 15 0.76%/1.40% 1.21%/2.94%1.99%/1.81% 2.20%/2.08% 0.28%/0.14% Sample 16 1.28%/2.14% 0.43%/0.86%1.27%/1.27% 1.53%/1.70% 0.42%/0.50% Sample 17 0.99%/1.28% 0.41%/0.99%1.43%/1.24% 1.83%/1.90% 0.54%/0.67% Sample 18 3.70%/3.77% 0.86%/1.19%3.56%/3.25% 3.29%/3.45% 0.71%/0.65% Sample 19 3.52%/3.84% 0.60%/1.04%3.14%/3.45% 3.48%/3.48% 1.08%/0.67% Sample 20 3.29%/3.60% 1.03%/1.41%3.07%/3.36% 3.35%/3.46% 0.91%/0.45% Sample 21 0.49%/0.55% 1.01%/1.24%Sample 22 0.91%/1.18% 0.85%/1.11% Sample 23 1.20%/1.45% 0.76%/0.84%

Comparative Example 6

[0078] This comparative example demonstrates that ene-thiol networkscontaining significant amounts of oxygen ether linkages have poorerresistance to ink, solvent, and water than Samples 1-20. ComparativeSamples CS 1-CS 10 were made by reaction of Oligomers 13-18 with eitherTAIC or TAC as shown in Table 13. The sample preparation procedure wasdescribed in Example 6. The solvent, water, and ink resistance of thecomparative samples are shown in Table 11. For each of these samples,the swelling in water/n-butanol and inks is higher than that shown inTable 13. The swelling of samples containing large amounts of oxygenether linkages is as high as 20 percent in water/n-butanol and 17percent in ink. TABLE 13 Oligomer Crosslinker Oligomer WeightCrosslinker Weight CS 1 Oligomer 13 11.19 g TAC 0.60 g CS 2 Oligomer 14 4.10 g TAC 0.77 g CS 3 Oligomer 14 12.28 g TAIC 2.30 g CS 4 Oligomer 1514.93 g TAC 0.92 g CS 5 Oligomer 16  4.06 g TAC 0.80 g CS 6 Oligomer 16 4.29 g TAIC 0.87 g CS 7 Oligomer 17 17.38 g TAC 1.07 g CS 8 Oligomer 1714.44 g TAIC 0.90 g CS 9 Oligomer 18  4.05 g TAC 0.76 g CS 10 Oligomer18  4.22 g TAIC 0.81 g

[0079] Comparative Sample CS 11 demonstrates that an elastomer made froma DMDO, a difunctional olefin, and a trifunctional olefin has poorersolvent and moisture resistance than samples made from dimercaptanscontaining no oxygen ether linkages. Comparative Sample CS 11 wasprepared as described for Samples 22 and 23. DMDO (9.03 grams), CHVE(3.28 grams), and TAIC (5.46 grams) were stirred together 500 ppm NPALand 0.5 percent IRGACURE 651. The liquid was poured into a {fraction(1/16)} inch glass mold and cured. The water/n-butanol and water uptakefor this comparative sample, shown in Table 14, is much higher than wasfound for Samples 22 and 23, which were made from DMDS and DMDT.

[0080] Comparative Absorption Data

[0081] For the comparative absorption performance data, shown in Table14, the standard swelling procedure was used. The percentage weight gainfor the inks was calculated from the formula: (swollen weight)−(originalweight)/(original weight). The corrected percentage weight gain inwater/n-butanol or water was calculated from the following formula:(swollen weight)—(dried down weight)/(dried down weight). To obtain thedried down weight, Comparative Samples CS 1-CS 10 were dried for 48hours, and Comparative Sample CS 11 was dried for 96 hours. TABLE 14Water/n-butanol Water (7 96/4 (7 day/15 day/15 day Composite (7 Cyan (7day/15 Black (2 day corrected) corrected) day/15 day) day) day/7 day) CS1 6.12%/6.25% 1.33%/1.80% 5.40%/5.29% 5.58%/5.37% 1.06%/0.57% CS 25.22%/5.22% 1.47%/1.96% 4.79%/4.85% 5.31%/5.47% 1.61%/1.54% CS 35.05%/5.39% 1.40%/1.88% 5.02%/5.02% 5.52%/5.59% 1.98%/1.67% CS 411.70%/12.68% 3.75%/5.00% 10.43%/10.71% 10.76%/10.70% 5.10%/5.31% CS 56.83%/6.04% 2.82%/3.60% 6.17%/6.17% 7.37%/7.14% 2.94%/2.76% CS 67.12%/7.68% 3.04%/4.20% 6.70%/6.59% 7.37%/7.62% 3.56%/3.56% CS 718.02%/18.58% 5.83%/7.10% 15.55%/15.49% 16.24%/16.02% 9.34%/9.09% CS 817.98%/19.62% 5.50%/7.13% 15.67%/15.33% 16.30%/16.30% 9.37%/9.37% CS 910.56%/11.46% 3.91%/5.11% 10.10%/9.97%  10.88%/11.87% 6.69%/5.47% CS 1011.08%/11.37% 4.07%/5.26% 10.84%/10.84% 11.03%/11.84% 5.76%/5.26% CS 114.68%/5.15% 1.94%/2.22%

Example 8

[0082] Example 8 is a comparison of selected samples having differentamounts of sulfur and oxygen present in the network. Example 8 featuresthe water/n-butanol, water, and cyan ink swelling of selected samplesprepared from oligomers having a theoretical molecular weight of 2800.The molecular weight between crosslinks for these samples isapproximately 3000. The swelling data for the selected samples issummarized in Table 15. Also included in Table 15 is the sulfur weightpercent and oxygen weight percent in the oligomer that was used toprepare in the selected samples. This example demonstrates that as theweight percent of sulfur in the oligomer backbone increases and theweight percent of oxygen in the oligomer decreases, the swellingperformance of the network improves. TABLE 15 96/4 water/n-butanol swellWater swell (7 day/15 day (7 day/15 day Cyan swell S weight % O weight %corrected) corrected (7 day/15 day) CS 1 18 17 6.12%/6.25% 1.33%/1.80%5.58%/5.37% Sample 18 26 11 3.70%/3.77% 0.86%/1.19% 3.29%/3.45% Sample 129 8.7 2.30%/2.08% 0.90%/1.31% 2.45%/2.38% Sample 15 33 5 0.76%/1.40%1.21%/2.94% 2.20%/2.08% Sample 9 38 0.88%/1.17% 1.20%/2.80% 2.29%/2.40%

Example 9

[0083] Example 9 is a comparison of selected samples having differentamounts of sulfur and oxygen present in the network. Example 9 featuresthe water/n-butanol, water, and cyan ink swelling of selected samplesprepared from oligomers having a theoretical molecular weight of 830.The molecular weight between crosslinks for these samples isapproximately 1000. The swelling data for the selected samples issummarized in Table 16. Also included in Table 16 is the sulfur weightpercent and oxygen weight percent in the oligomer that was used toprepare in the selected samples. This example demonstrates that as theweight percent of sulfur in the oligomer backbone increases and theweight percent of oxygen in the oligomer decreases, the swellingperformance of the network improves. TABLE 16 96/4 water/butanol WaterCyan S Weight % O Weight % (3 day/7 day) (3 day/7 day) (2 day/7 day) CS2 21 17 5.22%/5.22% 1.47%/1.96% 5.31%/5.47% Sample 19 28 13 3.52%/3.84%0.60%/1.04% 3.48%/3.48% Sample 3 33 7.4 2.01%/2.35% 0.63%/1.09%2.22%/2.53% Sample 16 36 4.2 1.28%/2.14% 0.43%/0.86% 1.53%/1.70% Sample11 41 0.58%/0.95% 0.30%/0.73% 1.55%/1.69%

Example 10

[0084] Example 10 demonstrates the low moisture permeability ofthioether containing networks when compared to similar networkscontaining oxygen ether linkages. In each sample, a difunctionalmercaptan was mixed with either TAIC or TAC, 0.5 percent photoinitiator,and in some cases 500 ppm NPAL. The samples were mixed thoroughly atapproximately 50° C. and then degassed in a vacuum oven. Each sample wassandwiched between two glass plates that had been coated with Teflontape. The plates were separated by spacers that were approximately 4mils thick. The samples were then passed through a Fusion processor at25 ft/min, five times on each side. Samples containing IRGACURE 651 asthe photoinitiator were cured with the Fusion D bulb, and samplescontaining IRGACURE 819 as the photoinitiator were cured with the FusionV bulb. Samples 24-32 were prepared in this way and are presented inTable 17.

[0085] The permeability test was based on ASTM D814. A “standard”circular die 75 mm in diameter was used to punch press specimens fromfilm samples ranging from 80 to 150 microns thick. Release liners wereused on both sides of the specimen to make it easier to handle andmeasure. This “sandwich” was measured in 10 locations, and the averagenet film thickness was recorded.

[0086] The specimens were carefully removed from the liners and placedonto fluoroelastomeric gaskets with an outside diameter (O.D.) of 75 mm,an inside diameter (I.D.) of 63.5 mm, and a thickness of 1.5 mm. Thegasket and specimen were then placed onto the flanged rim of an aluminumpermeation cup containing 100 mL of deionized water. The cup has avolume of 250 mL. A second gasket, 3 mm thick, was placed over the firstgasket and the specimen, and a 75 mm diameter piece of window screen wasthen placed on top of all three. This screen served to preventstretching of extensible materials.

[0087] The gaskets, specimen, and screen were held in place by acircular aluminum ring with an I.D. of 63.5 mm and an O.D. of 88 mm.Along the outer edge of this ring were six evenly distributed threadedholes, through which screws pass into the flanged rim of the cup. Thescrews were loosely put in place and the entire assembly placed into a40° C. oven. After allowing the assembly to equilibrate for 1 hour, thescrews were securely tightened, the cup was removed from the oven, andthe initial weight was taken. Weights were taken every day or so for thefirst week, about every third day the second week, and about every fifthday thereafter.

[0088] The permeability (g-mm/m²-day@40° C.), or moisture vaportransmission rate, was calculated by multiplying the film thickness (mm)by the total water weight loss (gram), and dividing by the area of thefilm (0.003167 m²) and the number hours divided by 24 (day). Thepermeabilities of Samples 24-32 are shown in Table 17. TABLE 17 TAICDimercaptan Weight (g) TAC (g) Initiator NPAL Permeability Sample 24DMDS  5.54 g 5.96 g — 819 Yes  9 Sample 25 DMDS 14.07 g — 15.16 g 651Yes 17 Sample 26 Oligomer 1  8.48 g 0.43 g — 651 No 48 Sample 27Oligomer 2 12.18 g 2.33 g — 651 No 35 Sample 28 Oligomer 4  7.96 g — 1.71 g 651 No 29 Sample 29 Oligomer 4  6.86 g 1.49 g — 651 No 24 Sample30 Oligomer 6 13.09 g 2.61 g — 651 No 18 Sample 31 Oligomer 9  7.25 g0.42 g — 651 No 35 Sample 32 Oligomer 10  5.09 g 0.98 g — 651 No 24

Comparative Example 7

[0089] This comparative example demonstrates the higher moisturepermeability of samples containing significant amounts of oxygen etherlinkages when compared to Samples 24-32. Comparative Samples CS 12-CS 15were prepared and measured as described in Example 10 and are summarizedin Table 18. TABLE 18 Dimercaptan Weight TAIC TAC NPAL InitiatorPermeability CS 12 DMDO 5.11 g 4.67 g — yes 651 55 CS 13 DMDO 5.36 g —4.88 g yes 819 52 CS 14 EBMP 6.63 g 4.61 g — yes 651 59 CS 15 Oligomer14 12.28 g  2.30 g — no 651 99

Example 11

[0090] Example 11 is a comparison of samples containing different weightpercentages of sulfur and oxygen in the network but containing the samemolecular weight between crosslinks. Each sample was prepared from anoligomer with a theoretical molecular weight of 830 and TAIC as thecrosslinker. For each sample, the molecular weight between crosslinks isapproximately 1000. This is important because the crosslink density ofthe sample greatly affects the permeability of the sample. The weightpercentages of sulfur and oxygen in the oligomers used to prepare thesamples as well as the moisture permeability are reported in Table 19.The data in Table 19 indicate that the permeability of samplescontaining the same crosslink density varies significantly with theweight percentages of sulfur and oxygen in the backbone. As the weightpercentage of sulfur increase and the weight percentage of oxygendecreases, the permeability of the sample decreases. This exampledemonstrates that the moisture permeability of ene-thiol networks can belowered by maximizing the amount of thioether linkages and minimizingthe amount of oxygen ether linkages in the backbone. TABLE 19 S Weight %O Weight % Permeability CS 15 21 17 99 Sample 27 33 7.4 35 Sample 32 364.2 24 Sample 30 41 0 18

Example 12

[0091] Example 12 demonstrates that the odor of thioether oligomers canbe decreased by the removal of volatile components. An oligomer of DMDSand CHVE having a molecular weight of 1700 was prepared by the thermalprocedure. This oligomer (320 grams) was heated to 80° C. and wasdropped into a UIC rolled film evaporator. The jacket temperature of thecolumn was 100° C., and apparatus was under a vacuum of 0.009 mm Hg. Twocold traps, a cold finger with a temperature of 20° C., and a liquidnitrogen trap to protect the vacuum pump, were used. The rollers wereset at a speed of 300 rpm. Following this treatment of the oligomer, 2.0gram of material were collected in the cold finger, and 3.3 grams ofmaterial were collected in the liquid nitrogen trap. The materialstripped from the oligomer was analyzed and found to contain mostlyresidual monomer and cyclic impurities from the monomer. The odor of theoligomer was significantly reduced. A second treatment of 225 grams ofthe oligomer was carried out with a column temperature of 150° C. Anadditional 0.22 grams of material was collected, and the odor of theoligomer was reduced further.

[0092] Other embodiments are within the following claims. While theinvention has been described with reference to the particularembodiments and drawings set forth above, the spirit of the invention isnot so limited and is defined by the appended claims.

What is claimed is:
 1. A curable composition for making an ene-thiolelastomer comprising a mixture of: (a) a polythiol free of hydrophilicgroups and having at least two thiol groups; (b) an aromatic,heterocyclic, aliphatic, or cycloaliphatic polyene having at least tworeactive unsaturated carbon to carbon bonds; and (c) a free radicalinitiator, wherein the composition in cured form, when immersed in asolution of 96 parts by weight water and 4 parts by weight n-butanol,shows a weight increase of not more than 4 weight percent in 15 days ata temperature of 22° C.
 2. The composition of claim 1 wherein the freeradical initiator is UV active or thermally active.
 3. The compositionof claim 1 wherein said polyene comprises allyl, vinyl, allyl ether,allyl ester, vinyl ether, styryl, cycloalkenyl, or (meth)acrylcompounds, or combinations thereof.
 4. The composition of claim 1wherein the polyene is triallyl-1,3,5-triazine-2,4,6-trione;2,4,6-triallyloxy-1,3,5-triazine; 1,4-cyclohexanedimethanol divinylether; 4-vinyl-1-cyclohexene; 1,5-cyclooctadiene; diallyl phthalate; ora combination thereof.
 5. The composition of claim 1 wherein the polyeneis a mixture of a polyene having two reactive unsaturated carbon tocarbon bonds and a polyene having three reactive unsaturated carbon tocarbon bonds.
 6. The composition of claim 1 wherein the heterocyclicpolyene is triallyl-1,3,5-triazine-2,4,6-trione;2,4,6-triallyloxy-1,3,5-triazine; or a combination thereof.
 7. Thecomposition of claim 1 wherein the polythiol has the formula:

where m=2-12, n=2-12, q=0-4, where m and n can be the same or different;or the formula H—S—R—S—H, where R=C₅-C₈ cycloaliphatic radical.
 8. Thecomposition of claim 1 wherein the polythiol is dimercaptodiethylsulfide; 1,6-hexanedithiol; 1,8-dimercapto-3,6-dithiaoctane; or acombination thereof.
 9. An ene-thiol elastomer comprising the reactionproduct of the composition of claim 1.